分布式事务与Seate框架(2)——Seata实践

时间:2024-02-01 11:48:55

前言

  在上一篇博文(分布式事务与Seate框架(1)——分布式事务理论)中了解了足够的分布式事务的理论知识后,到了实践部分,在工作中虽然用到了Seata,但是自己却并没有完全实践过,所以自己私下花点时间实践以加深理解,实际上在实践过程中遇到了很多的坑(比如Seata与SpringCloudAlibaba的整合中版本兼容性问题,是个很让人头疼的一块,甚至专门去github提过issue),有时候甚至得跟踪源码进行分析,这也使我加强了对阅读源码的能力。总之都是要code的。本篇博文主要结合实践深入讲解Seata AT模式!

  参考资料《Spring Cloud Alibaba 微服务原理与实战》(PDF电子书资源,有需要的小伙伴可以评论私信我)、官方wiki

  博文中源码已上传至github(https://github.com/Jian0110/learning-cloudalibaba),欢迎小伙伴们star...

 


 

一、实践准备工作

1、框架介绍

实践主要是以“订单-库存-账户”系统演示,主要的框架图如下,图中各个部分充当的分布式事务角色已标明。

    

  具体流程:

  1)用户登录XXX商品购物系统(假设已有账户),

  2)点击购买某个商品,发起创建订单请求;

  3)检查购买商品的库存量,如果不够则创建订单失败提示库存不足;否则锁定该商品---->减少库存--->创建订单;

  4)订单创建成功后点击付款(或直接付款无需点击,实际上整个Demo中下单之后模拟立马支付,并不会点击付款);

  5)如果购买成功则对账户进行余额进行判断,余额足够则进行减扣,余额不够则进行提示说明

  6)返回购买成功失败提示说明。

2、项目结构

项目结构如下:

mvn package打包运行seata服务,即运行TC服务器(这里只展示单机)

初始化Seata库,导入sql脚本

二、代码实践

这里只展示关键代码,全部代码已提交gituhb:,有需要的小伙伴可以自行获取

1、“订单-库存-账户”服务

订单服务:

    TM(microService):seata-order-service

    RM(DB Resources):jdbc:mysql://127.0.0.1:3306/order

OrderService:

@GlobalTransactional // TM开启全局事务
    @Transactional(rollbackFor = Exception.class)
    public void createOrder(Long productId, BigDecimal price){
        // 这里模拟获取的是用户的账户ID
        // 通过上下文获取userId再获取accountId(单个账户)
        Long accountId = 1L; // 假设已经获取到了账户ID

        // 1.rpc调用库存微服务检查库存并减库存操作
        Boolean deductStorageSuccess =  storageFeignClient.deduct(productId);
        if (!deductStorageSuccess) {
            throw new RuntimeException("storage deduct failed!");
        }
        // 2.创建订单
        ProductOrder order =  ProductOrder.builder()
                .productId(productId)
                .accountId(accountId)
                .payAmount(price)
                .build();
        log.info("create order : {}", order);
        // 这里为了模拟回滚,所以先对价格的判断放到了创建订单之后,抛出runtime exception
        if (price.compareTo(BigDecimal.ZERO) < 0) {
            throw new NumberFormatException("product price must greater than zero!");
        }
        orderMapper.insertSelective(order);

        // 3.rpc调用账户微服务对余额检查并扣款操作
        Boolean deductAccountSuccess =  accountFeignClient.deduct(accountId, price);
        if (!deductAccountSuccess) {
            throw new RuntimeException("account deduct failed!");
        }
        // 4. 反馈结果
    }

OrderController:

 /**
     * 模拟创建订单
     * @param productId
     * @param price
     * @return
     */
    @PostMapping("/create")
    public String create(Long productId, BigDecimal price){
        try {
            orderService.createOrder(productId, price);
        } catch (Exception e) {
            log.error("order failed: ", e);
            return "order failed";
        }
        return "order success";
    }

调用的Feign:

@FeignClient(name="seata-account-service")
public interface AccountFeignClient {
    @PostMapping("/account/deduct")
    Boolean deduct(@RequestParam("accountId") Long accountId, @RequestParam("payAmount") BigDecimal payAmount);
}


@FeignClient(name="seata-storage-service")
public interface StorageFeignClient {
    @PostMapping("/storage/deduct")
    Boolean deduct(@RequestParam("productId") Long productId);
}

库存服务:

    microService:seata-storage-service

    RM(DB Resources):jdbc:mysql://127.0.0.1:3306/storage

StorageService

public Boolean deduct(Long productId){
        // 这里先检查有没有库存了, 生产环境下这里是需要for update数据库锁,或者分布式锁
        Repo repoFromDB =   repoMapper.selectByPrimaryKey(productId);
        if (repoFromDB == null) {
            throw new RuntimeException("product not exist!");
        }
        // 对库存减一
        int afterCount = repoFromDB.getAmount()-1;
        // 没有库存剩余了
        if (afterCount < 0) {
            throw new RuntimeException("product storage is no remaining!");
        }
        Repo repo = Repo.builder()
                .id(productId)
                .amount(afterCount)
                .build();
        repoMapper.updateAmount(repo);
        log.info("deduct product[{}] storage, current amount is {}", productId, afterCount);
        return true;
    }

StorageController:

/**
     * 模拟对商品库存减一
     * @param productId
     * @return
     */
    @PostMapping("/deduct")
    public Boolean deduct(Long productId){
        try {
            storageService.deduct(productId);
        } catch (Exception e) {
            return false;
        }
        return true;
    }

账户服务

    microService:seata-account-service

    RM(DB Resources):jdbc:mysql:127.0.0.1/account

AccountService:

public void deduct(Long accountId, BigDecimal payAmount){
        // 这里先检查有没有账户存在, 生产环境下这里是需要for update数据库锁,或者分布式锁
        UserAccount userAccountFromDB =  userAccountMapper.selectByPrimaryKey(accountId);
        if (userAccountFromDB == null) {
            throw new RuntimeException("account not exist!");
        }
        // 检查余额是否足够
        BigDecimal afterBalance = userAccountFromDB.getBalance().subtract(payAmount);
        if (afterBalance.compareTo(BigDecimal.ZERO) < 0) {
            throw new RuntimeException("the balance is not enough!");
        }
        UserAccount userAccount = UserAccount.builder()
                .id(accountId)
                .balance(afterBalance)
                .build();
        log.info("deduct account[{}] , current balance is {}", accountId, afterBalance);
        userAccountMapper.updateBalance(userAccount);
    }

AccountController:

/**
     * 模拟账户扣款
     * @param accountId
     * @param payAmount
     * @return
     */
    @PostMapping("/deduct")
    public Boolean deduct(Long accountId, BigDecimal payAmount){
        try {
            accountService.deduct(accountId, payAmount);
        } catch (Exception e) {
            return false;
        }
        return true;
    }

2、Seata服务器,即TC角色

  首先初始化seata的sql脚本(sql脚本参考官方wiki),并开启seata库,之后开启Seata Server(具体的配置与启动前nacos配置,事务分组等相关概念请参考官方wiki)

    

3、检查Nacos服务与配置列表

  微服务模块启动后快速注册到dev命名空间下的SEATA_GROUP分组,此时TM、RM、TC都已经具备        

启动微服务模块后可以看到日志输出,说明启动成功并且已经成功注册

RM will register :jdbc:mysql://127.0.0.1:3306/account
nacos registry, SEATA_GROUP seata-account-service 192.168.99.1:6009 register finished
Started SeataAccountApplication in 30.115 seconds (JVM running for 33.158) ....... NettyPool create channel to transactionRole:TMROLE,address:169.254.6.29:8091,msg:< RegisterTMRequest{applicationId=\'seata-account-service\', transactionServiceGroup=\'my_test_tx_group\'} > register TM success. client version:1.4.0, server version:1.4.0,channel:[id: 0xa77dc065, L:/169.254.6.29:52794 - R:/169.254.6.29:8091] register success, cost 4 ms, version:1.4.0,role:TMROLE,channel:[id: 0xa77dc065, L:/169.254.6.29:52794 - R:/169.254.6.29:8091]

三、运行测试

1、模拟购买支付成功情况

运行启动所有的微服务后,在TC Serve的日志可以看到所有的TM、RM都已经注册了

此时productId=1库存还剩998

accountId=1的用户余额还剩1000元

 接下来就是模拟用户购买商品环节,调用http://localhost:6008/order/create,表示用户想买商品ID=1,价格为12.25的商品

清空日志,并发起请求查看日志:

16:10:45.167  INFO --- [rverHandlerThread_1_4_500] i.s.s.coordinator.DefaultCoordinator     : Begin new global transaction applicationId: seata-order-service,transactionServiceGroup: my_test_tx_group, transactionName: createOrder(java.lang.Long, java.math.BigDecimal),timeout:60000,xid:169.254.6.29:8091:136139747123908608
16:10:45.964  INFO --- [     batchLoggerPrint_1_1] i.s.c.r.p.server.BatchLogHandler         : SeataMergeMessage xid=169.254.6.29:8091:136139747123908608,branchType=AT,resourceId=jdbc:mysql://127.0.0.1:3306/storage,lockKey=repo:1
,clientIp:169.254.6.29,vgroup:my_test_tx_group
16:10:46.086  INFO --- [rverHandlerThread_1_5_500] i.seata.server.coordinator.AbstractCore  : Register branch successfully, xid = 169.254.6.29:8091:136139747123908608, branchId = 136139750928142336, resourceId = jdbc:mysql://127.0.0.1:3306/storage ,lockKeys = repo:1
16:10:46.788  INFO --- [     batchLoggerPrint_1_1] i.s.c.r.p.server.BatchLogHandler         : SeataMergeMessage xid=169.254.6.29:8091:136139747123908608,branchType=AT,resourceId=jdbc:mysql://127.0.0.1:3306/account,lockKey=user_account:1
,clientIp:169.254.6.29,vgroup:my_test_tx_group
16:10:46.918  INFO --- [rverHandlerThread_1_6_500] i.seata.server.coordinator.AbstractCore  : Register branch successfully, xid = 169.254.6.29:8091:136139747123908608, branchId = 136139754342305793, resourceId = jdbc:mysql://127.0.0.1:3306/account ,lockKeys = user_account:1
16:10:47.015  INFO --- [     batchLoggerPrint_1_1] i.s.c.r.p.server.BatchLogHandler         : xid=169.254.6.29:8091:136139747123908608,branchType=AT,resourceId=jdbc:mysql://127.0.0.1:3306/order,lockKey=product_order:6,clientIp:169.254.6.29,vgroup:my_test_tx_group
16:10:47.073  INFO --- [rverHandlerThread_1_7_500] i.seata.server.coordinator.AbstractCore  : Register branch successfully, xid = 169.254.6.29:8091:136139747123908608, branchId = 136139755294412801, resourceId = jdbc:mysql://127.0.0.1:3306/order ,lockKeys = product_order:6
16:10:47.184  INFO --- [     batchLoggerPrint_1_1] i.s.c.r.p.server.BatchLogHandler         : xid=169.254.6.29:8091:136139747123908608,extraData=null,clientIp:169.254.6.29,vgroup:my_test_tx_group
16:10:48.084  INFO --- [      AsyncCommitting_1_1] io.seata.server.coordinator.DefaultCore  : Committing global transaction is successfully done, xid = 169.254.6.29:8091:136139747123908608.
16:10:53.908  INFO --- [       TxTimeoutCheck_1_1] i.s.s.coordinator.DefaultCoordinator     : Global transaction[169.254.6.29:8091:136139530647490560] is timeout and will be rollback.
16:10:54.947  INFO --- [     RetryRollbacking_1_1] io.seata.server.coordinator.DefaultCore  : Rollback global transaction successfully, xid = 169.254.6.29:8091:136139530647490560.

从日志中我们可以看到:

1)全局事务XID已经生成,各个分支注册成功,

2)branchId也已经生成并在全局事务XID下,资源已被锁住

3)全局事务提交成功

查看此时的库存与余额,都已经进行了减扣

2、模拟库存不足情况

修改productId=1的商品库存为0:

再次发起请求,查看TC Server日志,可以查出明显发生了全局事务的回滚

16:20:24.258  INFO --- [verHandlerThread_1_12_500] i.s.s.coordinator.DefaultCoordinator     : Begin new global transaction applicationId: seata-order-service,transactionServiceGroup: my_test_tx_group, transactionName: createOrder(java.lang.Long, java.math.BigDecimal),timeout:60000,xid:169.254.6.29:8091:136142176250875904
16:20:24.279  INFO --- [     batchLoggerPrint_1_1] i.s.c.r.p.server.BatchLogHandler         : xid=169.254.6.29:8091:136142176250875904,extraData=null,clientIp:169.254.6.29,vgroup:my_test_tx_group
16:20:24.420  INFO --- [verHandlerThread_1_13_500] io.seata.server.coordinator.DefaultCore  : Rollback global transaction successfully, xid = 169.254.6.29:8091:136142176250875904.

查看库存与余额情况,库存仍然是0,余额仍然是987.75

3、模拟余额不足情况

修改accountId=1的账户余额小于12.25

再次发起请求,查看日志

16:27:41.811  INFO --- [verHandlerThread_1_14_500] i.s.s.coordinator.DefaultCoordinator     : Begin new global transaction applicationId: seata-order-service,transactionServiceGroup: my_test_tx_group, transactionName: createOrder(java.lang.Long, java.math.BigDecimal),timeout:60000,xid:169.254.6.29:8091:136144011456008192
16:27:41.836  INFO --- [     batchLoggerPrint_1_1] i.s.c.r.p.server.BatchLogHandler         : SeataMergeMessage xid=169.254.6.29:8091:136144011456008192,branchType=AT,resourceId=jdbc:mysql://127.0.0.1:3306/storage,lockKey=repo:1
,clientIp:169.254.6.29,vgroup:my_test_tx_group
16:27:41.889  INFO --- [verHandlerThread_1_15_500] i.seata.server.coordinator.AbstractCore  : Register branch successfully, xid = 169.254.6.29:8091:136144011456008192, branchId = 136144011762192385, resourceId = jdbc:mysql://127.0.0.1:3306/storage ,lockKeys = repo:1
16:27:42.088  INFO --- [     batchLoggerPrint_1_1] i.s.c.r.p.server.BatchLogHandler         : xid=169.254.6.29:8091:136144011456008192,extraData=null,clientIp:169.254.6.29,vgroup:my_test_tx_group
16:27:42.632  INFO --- [verHandlerThread_1_16_500] io.seata.server.coordinator.DefaultCore  : Rollback branch transaction successfully, xid = 169.254.6.29:8091:136144011456008192 branchId = 136144011762192385
16:27:42.754  INFO --- [verHandlerThread_1_16_500] io.seata.server.coordinator.DefaultCore  : Rollback global transaction successfully, xid = 169.254.6.29:8091:136144011456008192.

不同于库存不足的情况的是,这里库存服务分支事务是先注册TC Server的,因为有异常的并不是库存服务,需要注意的是因为我模拟的是下单之后立马支付,支付失败的话订单也是不会存在,实际生活中应该是订单显示“支付失败”。

查看库存与余额情况,库存仍然是997,余额仍然是10.75